Background
Chromium is an essential trace mineral. It exerts its beneficial effect by assisting the action of insulin. Chromium, as part of the organic complex known as glucose tolerance factor (GTF), works together with insulin to clear the blood of glucose.
The justification for supplementing chromium in a population of people with type 2 diabetes lies in the mechanism that removes chromium from the body. As glucose collects in the plasma after a meal, insulin and the chromium complex are released. Chromium released is eventually excreted from the body in urine. The more glucose that resides in the plasma, and the longer it remains here, the more chromium is mobilized, and the greater the chromium losses from the body. Consumption of diets high in refined carbohydrates have been shown to raise urinary chromium losses by as much as 300%. A normal loss of 1 mcg chromium per day could in some individuals, especially those with abnormal glucose tolerance, increase to 300 mcg's per day.
There is no RDA for chromium. The government has established an Estimated Safe and Adequate Intake for chromium at between 50 to 200 mcg per day. Since chromium losses could surpass this in certain individuals, the authors of this study investigated the effects of supplementation at both 200 mcg/day and 1000 mcg/day.
Study Results
A total of 180 men and women from Beijing, China who were being treated for type 2 diabetes were recruited for the double-blind study. A third of the participants received a placebo, a third received 200 mcg Cr/day, a third received 1000 mcg Cr/day. Chromium was supplied as chromium picolinate. Nutrition 21, the chromium supplier and manufacturer, claimed that this formulation of chromium was better absorbed than others. The study lasted four months.
A total of 155 subjects completed the study. Glycosylated hemoglobin (HbA1c) improved significantly in the group receiving 1000 mcg/day with values approximately 20% lower than placebo. Blood glucose values declined in both the 200 mcg/day and the 1000 mcg/day groups. Those receiving the higher amount of chromium experienced greater results with values approximately 15% to 19% lower than placebo.
Total cholesterol decreased in subjects receiving 1000 mcg/day but the effects of supplemental chromium were greater for glucose and insulin than for lipid concentrations. The study found no significant changes in HDL cholesterol, triglycerides, blood urea nitrogen, weight, or BMI.
The researchers of this study concluded that supplemental chromium had pronounced beneficial effects on glucose and insulin in people with type 2 diabetes. They stated that 200 mcg of chromium per day "did not appear to be sufficient for the reversal of diabetic symptoms", and that "larger consistent effects were observed in subjects receiving 1000 mcg Cr daily." The researchers fell short of actually recommending supplementation for this population at the higher 1000 mcg level.
Comments
Diabetes is not defined as a chromium deficient disease. It was thought that only chromium replacement to within the US Estimated Safe and Adequate Daily Dietary Intake (ESA) of 50 to 200 mcg/day would have beneficial effects on blood glucose. This could have accounted for the positive effects seen in the 200 mcg group. An intake of 200 mcg/day may have overcome marginal or deficient chromium status in this population. However, this study demonstrated that intakes above the upper limit of the ESA relayed additional benefits.
The article was wise to address the safety of large intakes of chromium. In March 1997, 8 months prior to the publication of this article, the Annals of Internal Medicine published a letter** describing a patient who developed renal failure after ingesting 600 mcg chromium picolinate daily for 6 weeks. The authors warned of possible adverse effects given Nutrition 21's aggressive advertising campaign promoting chromium picolinate as, among others, a promoter of lean muscle mass and a therapy for weight loss. They recommended warning labels and increased regulation by the FDA.
It cannot go without mentioning that Nutrition 21, the company who manufactured and supplied the product under investigation, and who assisted in analysis of data, serves to benefit from a positive outcome in this study.
There were many aspects to recommend this study as significant not only in the field of nutrition but as a therapy base for a disease, type 2 diabetes, that in the US is reaching epidemic proportions. Although the body of study was small, the results were statistically and clinically significant. It should prove a strong instigator for further study, and to that end was presented at the annual meeting of the American Diabetes Association in June 1996.
Special Note
People with diabetes who are on insulin or other diabetes medications should check with their doctors before supplementing with chromium. Because chromium may decrease insulin resistance, it may change the type or amount of medication needed to treat the diabetes and the frequency with which blood sugar needs to be monitored. This is especially important for those under tight blood glucose control. Supplementing chromium in this situation has the potential to cause low blood sugar (hypoglycemia).
** Wasser WG, Feldman NS, and D'Agati VD. Chronic renal failure after ingestion of over-the-counter chromium picolinate. Annals of Internal Medicine. 1997; 126(5): 410.